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Help with choosing.

I currently have Hunter PGM rotors installed. I have only had them a couple of years now and they seem to work ok but I have a problem when my system turns on. It bangs through the house really loud like water hammer but only when the zones turn on and not off. After 2 years of trying to figure this out I think that what is happening is that the water drains out of the PGM's and puts air back into the pipes. Then when the valve opens the water tries to RUSH into the lateral pipes to the sprinkler heads and cant do it correctly so it causes banging trying to get more water. Does this sound right?

So I think if I get NEW rotors with check valves built in then the water wont drain out, causing no air to go back into the pipes. Which also means my lateral pipes will be pressurized (I think) and then when the valve opens it just has to push the water, not try to push the air out and fill the pipes with water as well.

I hope this will fix my 2 year problem. I cant water early in the morning cause of the banging in the house for a few seconds each zone.

So would the RAINBIRD 3500 with the sam work? They are priced reasonably. What is up with HUNTER? There PGJ, PGM, and PGP rotors all say OPTIONAL check valve installed. How do you order these with check valves? Sprinkler wherehouse is where I am going to buy them cause of the prices. Can I get the PGP which is on sale with the check valves?

If that is the problem, installing the sprinklers with the check valves should help reduce the amount of water hammer. Your pipe size has a lot to do with it as well. Too small of pipes and too much pressure can cause water hammer. I believe you can get the PGP's with a check valve on them for a little bit more money.

If you have more pressure than you need for the sprinklers to operate, you might experiment with restricting the flow into the system, to see if it affects the water hammer. Another thing to do, and you should do this anyway when a sprinkler system causes water hammer, is to install a pressure reducing valve in the house line after the point where the lawn sprinkler supply tees off. The closer this point is too the water meter, the less of your household plumbing there is to rattle. Of course, the sprinkler pipe should be solidly braced, so its bumps and rattles don't sound too loud.

The water hammer device may or may not help. It definitely will absorb some of the shock, but it may not absorb it all. Get to the root of the problem..sounds like your water source is undersized to me.